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(No Model.) 2 Shets-Sheet '1 'W. E. PRAL'L.

I v METHOD OF SUPPLYING HEAT AND POWER. I 8 No. 376,830. PatentedJan.24; 1888.

. Attorney L v I IIIIIIIIIIIIIIIIIIIIII. 0.3 diam/m 2' Sheets -She'et 2.

(No Model.)

W. E. PRALL. METHOD OF SUPPLYING HEAT AND POWER.

No. 376,830.' Patented Jan. 24, 1 888;"

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WITNESSES ,5 6. Km imw w N. PETERS Phulmulhcgrnphsr. Wnhinglon. DcQ

- UNITED STATES WILLIAM E. PRALL, OF WASHINGTON, DISTRICT OFOOLUMBIA,AssIGNoR TO THE PRALL UNION HEATING OOMPANY, OF NEW YORK,1N. Y.

'MeTHoo'o F SUPPLYING HEAT ANDVPOWER.

SPECIFICATION forming part of Letters Patent NO. 376,830, dated January24,1888. I I Application filed December 20, 1861- Serial No. 258,464.(No modelJ Patented in England July 23,1879, No. 2,987. 7

To all whom it may concern.-

Be it known that I, WILLIAM E. PRALL, a citizen of the United States,and a resident of Washington, in the District' of Columbia,

have invented a certain new and useful Method for Supplying Heat andPower to large Districts of Buildings in Cities and Towns, .of which thefollowing is a specification.

' This invention relates toa-novel method of 13 conveying heat for thepurpose of warming large districts of buildingsin cities and towns, andto the manner of utilizing and distributing the same from onecommonsource of sup-- ply, and embodies a safe, economical, conven- I 5 ient,and healthful system of delivering and controlling the heat in each andevery building and compartment therein, and of supplying motive powerfor propelling street-cars, stationary engines, and for other purposes.

Figure 1 is a part sectional view of a heating tank or boiler andpreheater or water heater; also, of a hot-water circulating main and abuilding fitted up with radiators connected with an apparatus forconverting the hot water when taken from the main pipe into steam, andtraps for returning the water of condensation to the circulating main.Fig. 2

shows a plan view of the heaters and circulating pumps, together with aview of the I pipes conveying hot water through different streets, andpipes for returning the water of condensation, and a pump for forcingthe same into a preheater, and thence directly into the heater fromwhich it was previously taken. Fig. 3 shows three modifications of theapparatus for taking the hot water from the main and utilizing the samefor heating buildings, 'as well as arrangements for metering the'same.Figs. 4:, 5, 6, 7, 8,'aud 9 are de- 40 tail drawings of apressure-regulating valve, temperature and balance valve for controllingthe exhaust-water from the radiators, and means for draining thecirculating-pipes and an apparatus for measuring steam.

5 In Fig. 1, A represents a hot-water tank or heater, and should be ofsufficient capacity to furnish all the hot water that would be requiredfor supplying heat to the district reached by the circulating pipe ormain 0,- said pipe being connected thereto at or near the bottom,certainly below the water-line.

able building convenientto the district to be being also connected withG, which is,;iu

The heater is provided with a constant 'supply of water by means of apumping-engine from any convenient source in such quantities as isneeded to keep up the wasteffrom 5,5 the main pipe, which may be drawnfrom it for any purpose whatever. The power for driving thepumping-engine may be taken from the steam generated in theWater-heater, or it may, be taken from any other boiler erected for thatpurpose. It is evident that there may be several of thewater-.heaters-employed for the purpose of supplying water forcirculation, and they may all be conuected,or they may be separated, bymeans ofcocks V placed in the connecting-pipes, so that one'or more ofthem may be used independent of, the others; A

In the practical operation of this invention the water-heaters shouldbelocated in a suitsupplied with heat, and the circulatingpipe 0connected with-the force-pump B, said pump fact,the same from itsconnectionwith the 7 5 heater A, extending through the force or citculating pump B, and from thence through 1 one street and returningthrough another, as:- represented, and terminating again in the.

heater, the purpose of the force-pump B being only that of circulatingthe hot water, taking it fromthe heater under pressure and returningitagain for the purpose of reheating, and t the pump will be keptoperating with suflicient rapidity to cause the flow of water to 8.5 berapidenough to convey heat without much reduction of temperature alongthe entire length of the pipe. Other means maybe employed to circulatethe water through the pipesrs, for instance, the two ends maybe]connected with difierent heaters having a'dif ferent-pressure, and thusthe hot water may be forced from the one having the greater pressurethrough the pipe connecting it with the i V heater of lesspressurew Itisevident that various means maybe employed for circulating water; hence Ido not confine myself to any particular manner,and T in some placeswhere theamount drawn from the pipe was sufficiently greatthe flow might'be enough to keep the temperature high atthe farthest end without thenecessity of returning too it to the heater, and in that case no returnpipe or force-pump would be required; but the evident advantage ofcirculating the water is so apparent as to make the adoption of a singlepipe only a possibility. The street-mai n is to be covered with somenon-conducting substance to prevent as much as possible the radiation ofthe heat therefrom, and is also provided with expansion and contractionjoints to allow for the movement of the main pipe longitudinally. Themanifold advantages of thus conveying heat great distances will beeasily comprehended, because, as the weight or body of a cubic foot ofwater (or any given quantity) is at the boiling or steamgenerating pointseventeen hundred (1,700)

times as great as the steam thrown off at that temperature, it followsthat it contains a far greater number of units of heat. Thus it will beseen that a much larger amount of heat may be delivered through a pipeof great distance without loss from condensation than could be effectedby means of steam; and the hot water may by this process be convertedinto steam or otherwise used for the purpose of heating buildings at thepoint where required and overcome the great difficulty which hasheretofore prevented the heating of buildings located at a distance fromthe generator, at the same time affording a much more convenient andeconomical means of heating than by separate fires and generatorslocated in each building, and also avoiding much risk from danger byfire.

In Fig. 1, A represents a hot-water tank or heater, which should be ofsufficient capacity to furnish all the hot water that would be requiredfor supplying heat to the district reached by the circulating pipe ormain 0, said pipe being connected thereto at or near the bottom eitherdirectly or indirectly via the preheater A, as shown by thepipeconnect-ions and the arrows. B represents a circulating-pump, whichis connected with the pipe 0 at some point between the connections ofthe two ends of the same with the heater A, the purpose of which is tocause the hot water to move through the said pipe and be returned to theheater again, and it may be placed at eitherend of the circulating-pipe.The power for running it may be derived from any source whatever. Thepump B may be placed in the pipe connecting the preheating-tank with themain heater, and as it would take the water from the preheater the hotwater would be forced from the heater In the illustration, D representsa tank connected with the hot-water pipe 0 by means of branch pipes Dand D", said pipes being arranged to unite the tank D with thecirculating-pipe O at the same point, either very near together, asshown by pipes D and D", or a greater distance apart,by attaching one tothe outfiowing end of the pipe 0 and the other to the infiowing end ofthe same, as shown by pipes D and D.

X represents another tank placed within the tank D, leaving a spacebetween the two.

F is the pressureregulating valve in the pipe connecting the tanks D andX. 7

E- is a pipe connecting with the interior tank, X, and extends to theradiators F in the different parts of the house.

F is the condensed-water pipe, extending from the bottom of theradiators to the discharge-valve E and thence to the circulating pipe 0.

E represents a meter of any kind connected with the discharge F 0represents a cock or valve, which may be i used to increase or diminishthe size of the pipe 0, for the purpose of controlling the pressure andthe rapidity of the circulation in said. pipe. I

If the heater A be now filled with water, and by means of the fire inthe furnace is heated to a high degree-for example, say 332 Fahrenheit,which would give a pressure of about one hundred pounds to the squareinch, and be kept at that point, which would be120 abovethesteamgenerating pointand ifthe connections at both ends ofthecirculating water-mains be opened,the pressure upon them and the watertherein will be the same as upon the water in the heater and preheater,and if the force-pumpbe put in motion it will cause the water to beforced through the pipe by taking it from the heater and by dischargingit again into the same through the return-pipe and through thepreheater. The result will be to soon establish a temperature of aboutthe same degree to the water in the main pipe its entire length as thatin the heater. If, now,the cocksin the pipes Dand D be opened, the hotwater under pressure will flow from the main pipe 0 into the outsidetank, D, and surround the inner tank, X; and if the regulating-valve Fbe constructed to establish a ratio of difference in pressure that maybe desirable the water from between the tanks D and X will flow into Xthrough the valve and connecting-pipe F; but as soon as a small quantityhas entered the tank X the reduction of pressure established by thedifferential valve will cause the hot water so admitted to be convertedinto steam, as it contains many degrees of heat above thesteam-generating point, as before mentioned. As soon as the quantity ofwater thus admitted, however, has been evaporated into steam, the spacein the tank-X will be filled under pressure, which will act upon thedifferential valve F and close it and prevent the further admission ofators connected thereto andheat the'same; but

the cold air surrounding them conveys away theheat, and the steamtherein will be condensed, and thus the amount of water admitted intotank X will be converted into steam and conducted to the radiators. Thecondensed water, therefore, will be conducted through the pipe F 'an'dthe temperature-discharge valve E to the meter E and thence to the pipeOagain-" As soon as .condensation has reduced the steam-pressuresufficientlyin tank X and connecting-pipes and radiators, more hot waterwill beadmitted through the differential valve F into tank X, and thusthe supply will be kept constant. The hot water admitted into tank Xwill not be converted into steam by means of its own specific heat, andhence the purpose of surrounding the converting-chamber X with the hotwater in tank;

D, the heat of which will cause all the water admitted into tank X to beevaporated. The

purpose of connecting pipes D and D is to unite tank I) withth'emain'pipe O,fand thus produce circulation, for it will be seen thatas the water in said tank transmits itsheat into the water which isadmited into the interior tank, X, its temperature thereby will beproportionately lowered, and hence heavier, and

circulation will thus be established between the hot-water pipe 0 andthe tank I) through pipes D and D, and by means of this circulation atemperature will be maintained in said tank nearly the same as in thepipe 0.

If the cock in the circulating-pipe G be partially closed and the pumpBis keptin operation with sufiicient rapidity to remove the waterfromthe 'endot'pipe G faster than it is permitted to flow through thecontracted opening in the pipe at the cock 0, the result would be tomake the pressu'r'e'less in there.

turn end of the circulating pipe C, and'thus increase the rapidity ofcirculation through the pipes D and D as well as 'from thecondense-water pipe; or if the circulating-pump is placed at theoutflowing end of the circulating' -pipe O the effect would be toincrease the pressure in that end'above that of the in- ,fiowing end,which would have the same effect to increase the circulation through thebranch pipes connected thereto.

The manner of utilizingto the best possible advantage all the heat inthe coal in preheating the water'before it is admitted into the mainheater is accomplished, as shown in Fig. 1, by placing the preheaterabove the main heater in such a manner that the heat will pass throughthe preheater after passing through the main heater. In this mannerallthe Water from the return-pipe, which is of a lower temperature thanthat in the heater A, will be caused to pass through the preheater. InFig. 2 I have shown a plan for. circulating hotwater around severalblocks of buildings and means for controlling the How in each and everysection, and also a system of returnpipes connected with the mainhot-water pipes by the connectingpipes from the radiators,

and connections between the hot-wateror sup-v plypipes and thereturn-pipes maybe made at the connections K at the junction of thestreets, if desired. I have alsoshown in this figure a doublc-cylinderedpump, one used for v circulating the hot water and the other for takingthe return water from the pipes and forcing it into the heater orpreheater. In this figure, H designates the supply-pipe, and K.

the return pipe, and the circulation isas indicated by the arrows. It isevident that by the circulation in any ofthe cross-pipes may be cut offor controlled. L is the pipe which 'means'of cocks or valves. at theconnections K connects the supply-pipe of the street with the building,and M the pipe which. returns the water to the return-pipe of thestreet, by which it is reconveyed to the heater. It is evident the pipesexcept that drawnoff fordomestic purposes, as all the condensed waterwould be returned for reheating, and to supply the amount so drawn fromthe pipes the pumpH will supply fromany convenient source. It is evidentthat a force-pu mp may be employed to cause circulation in thereturn-pipe, and

'that the pumpB may be placed at eitherend ofthe supply-pipe. F

In Fig.3 I have shown several other modesof arranging the pipes andconnections for thrown off by the reduction of pressure by" 7 means ofthis valve is conveyed to, the radiatorsconnected thereto by meansofpipes. The

' water admitted to the evaporator through the too I the firstbuilding,wateri's adregulating valve which; is not converted into steam isconveyed through the hot-water'coil connected therewith, and thencethrough the discharge valve or trap 0 into thereturnpipe N, which maybeone continuous circulating-main, as shown in Fig. 1; or it may be aseparate pipe connected with the supplymain' only by means of the branchpipes, as shown in Fig. 2, these branch pipes being also connected withthe radiators, and the return water maybe'taken therefrom by thes'nction-.

pump and forced into the preheater and thence, into the main heater, asshown in Fig. 2. The meter 0" will register the amount'of water forcedthrough the pipe 0, and as the trap O is made to prevent the dischargeof the con:

dens'ed water only after it has had its temperature reduced to a certaindegree, it becomes an easy matter of calculation to determine the amountof heat consumed. I have'also shown I in this figure means forextinguishing fires in I I,

85 that very little Water would be wasted from buildings provided withthis system, which consists of a suitable hose or flexible pipe, whichis connected with the supply-pipe, as shown, and atall times when thesystem is in operation any fire within reach of the hose may be easilyextinguished. In the second building of this figure the apparatus is thesame, except the air conveyed into the rooms is admitted to the cabinetcontaining the coil, and after being heated is delivered through thedues extending therefrom into the various apartments. In the thirdbuilding of this figure is shown an arrangement of the pipes andradiators in a manner to utilize the hot water under full pressure. Thisplan has some advantages over that of steam for heating purposes, inthat it can be controlled by means of cocks or valves in such a manneras to keep the temperature of the radiators at any desired degree,whilewith steam it must either be at its full heat or entirely out off. Allwho have used steam have been inconvenienced by this lack of control ofthe heat. Then, again, the noise occasioned by the condensation of steamis entirely avoided when hot water is used directlyin radiators. I havealso shown in the figure an engine which can be run for power directlywith hot water, and by exhausting into the return-pipe be quite aseconomical and operative as when run by steam,

as all condensed water will be conveyed back to the heater. There is noditiiculty in working water at a high temperature in an engine properlyconstructed and arranged to exhaust in this manner, provided the cut-offis arranged to work very expansively and at a low pressure and finelywire-drawn or dissipated.

The meter will determine the amount of water consumed as in any otheroperation.

In some of the illustrations I haveshown the meter in position tomeasure the condensed water from the radiators. This plan, however, isnot considered very practical as a means of determining with any degreeof accuracy the amount of heat consumed, as the many accidental leaks,to say nothing of those purposely left in that condition, would easilyallow of a very great discrepancy, as one cubic foot of condensed waterwould represent nearly a thousand cubic feet of steam; hence greatopportunity would beafl'orded to practice imposition by means of themany cocks, valves, andjoints in and about the house. The only accurateway when steam is used in a building is to meter the water first beforeit has entered any of the pipes and radiators connected therewith.

'Fig. 4 represents a pressure regulating valve. It is constructed byfitting a movable plug, B, into the cylinder or barrel R", the plughaving a recess turned or cut in it about the center, whichcommunicates, by means of openings, with the tank R to which the case Itis fastened. The plug has a stem extending outward through the cap ofthe cylinder R, which carries a weight, It. In the practical operationof this valve, the pressure-pipe B being opened, the hot water isadmitted from the main pipe through the branch pipe and meter connectedtherewith, as shown in the first and second buildings of Fig. 3 Thecommunication being opened, the hot water will pass freely into the tankor converting-chant ber R but upon entering the said-tank the pressurewill be immediately relieved and steam will be generated, the pressureof which will act upon the plug R, and as soon as the pressure hasexceeded that of the weight R the plug will be thrown up. and theinlet-port from the pipe R will be cut off and the further admission ofhot water will be prevented; but as condensation is constantly going onin the radiators which connect with the convert ing-chamber R", thepressure will soon be so far reduced therein that the weight R will begreater than the sustaining force of the steam on the face of the plugIt, and it will begin to descend again. This movement will expose theinlet-port,and a further admission of hot water will be permitted, whichwill again be converted into steam, and in this manner a constant andnearly equal pressure will be maintained in the tank orconverting-chamber R and radiators connected therewith, irrespective ofthe pressure in the main or hot water pipe.

' In Fig. 9 I have shown a detached view of an apparatus to be used inconverting the hot water into steam for running engines, which isdesigned for use at such times and places where steam only is requiredfor power. V represents aconvertingtankflnto which thehot water isadmitted directly from the main pipe V through the meter Vand reducing-valve'V Said converting-tank is constructed with partitions V,extending perpendicularly or otherwise in such a manner as to cause thewater to pass through a considerable distance before it is finallydischarged into the trap U and into the return-pipe U, said partitionsbeing of no unequal height and left open at their tops for the escape ofsteam, as shown in the drawings, the object being to retain the waterfor a sufficient length oftime to enable the steam which is evaporatedby the specific heat of the water to be thrown off before the condensedwater is discharged into the return-pipe, and in that manner to enable anear approximation of the amount of heat or steam consumed to be made,for it will be seen that ifa given amount ofwater is admitted into theapparatus at a given temperature and discharged only after it has beenreduced to a very much lower temperature nearly all the steam thrown offand used could be determined.

In this apparatus the hot-water inductionport would be controlled by thegovernor of the engine, and in that way the power would be regulated.The trap shown in Fig. 7 would be the proper kind of thing to use withthis apparatus, as it would carry away all the water as fast as it wasallowed to pass through the converting-tank, but would not permit the Iescape of any steam, whereas an expansion or through the valve T.

temperature trap could hardly be regulated so satisfactorily in suchcases as where the water would be required to be discharged above thesteam-generating point, as required for power purposes.

In Fig. 5 is shown one form of a temperature steam-trap. It consists ofa 1ong copper(or other soft-metal) tube, S, which is arranged to conveythe water of condensation from the radiators. There are two bars orrods, S extending the full length of the tube S, which are attached tothe same base. These rods carry on their opposite ends a fixed valve, T,which communicates with the valve-seat, constructed on the end of theexpansion-tube S. Adischarge-pipe, T, is attached to the expansiontube,to convey away'the water which passes In the operation of this trap thewater of condensation will pass into the tube S, and will by its heatexpand the same and cause it to close the opening or valve T; but assoon as it has become sufficiently cooled the contraction of the pipe ortube will permit the water to pass out. As soon as the water begins torun hot through the tube, it will again expand and close the valve. Bythis means the water of condensation can be discharged at almost anytemperature from the radiators, and thus the entire heat of the wateradmitted may be utilized in warming the building. In Fig. 6 I have shownone manner of protecting the pipes under ground from radiation bycovering them by some well-known non-conductor and inclosing them in awooden box, W, arranged with a space, W, to carry off thewater thatotherwise might come in contact with the pipes and covering. The spaceor channel W is in communication'with the street-sewer W 'by means of apipe, 10.

In Fig. 7 I have shown a trap for discharging the water from theradiators. It is connected with the branch pipe B, leading to the streetreturn-pipe. It is constructed by place 'ing a movable diaphragm, Bbetween two concave cases, B andthen bolted together,

thus holding the diaphragm firmly in its posi-.

tion. To this diaphragmis fastened a stem, B, carrying a valve, B whichopens and closes a port constructed in the barrel B", said barrel beingrigidly attached to the lower side of the case B. 7 The pipe B, whichextends to the return-main, is connected below the valve, as shown. Thebarrel B is also connected, by

means of a pipe, B wit-h the bottom of the radiator or drip-pipe B",this latterconnection being made with the barrel above thedischarge-valve.- A pipe, B,textends from the drip-pipe to the upperside of the diaphragmcases. There is also a "pipe, B, extending from thelower side of the diaphragm-cases and connected to the upper end of theradiator or to a pipe extending upward from the drippipe.

B and B arranged, as shown, to extend above and below the diaphragm, andwhen In the operation of this trap it should be placed at the positionwhere the water of condensation will flowinto it, and the pipes full ofwater said pipes will regulate the movements of the same, and therebycontrol the discharge-valve. v 7

It is evident that if thewatcr should be drawn off from the radiators orfrom the connecting-pipe B", and the column of water in B were retainedby reason of the connections with the lower side of the case B thepressure of the column upon the increased area of thediaphragm wouldcause it to move in an upwardidirectiou and'carry with it the valve 13?,and thus prevent further discharge of water from the pipe B". So soon,however. as the accumulation of water in the pipeiB. and connecting-pipeB has brought about an equilibrium of pressure inthe pipes B and B,

the diaphragm will drop by the weight con- 3 nected thereto, and thevalve B will again be opened and the water permitted to fiow-out,

and thus the operation will continue alternately.

In Fig. 8 1 a valve for regulating the pressure. system for conveyingheat and power thepipes are to be provided with cocks or valves, asshown in Fig. 2, so that any section may be closed for repairs withoutinterfering in any way with the constant supply which ca'n'be furnishedthrough. other pipes connected thereto at the junctions of the streets.This system will not only furnish power for running all kinds ofengines, elevators, and heat for warming buildings, but it may also beemployed through the agency of a steam or hotwater stove for all kindsof cooking and other culinary purposes, and thus a. convenient,

have shown one construction of In thisv root.

heathful, and economicalsupply of heat and power may be delivered andutilized at a great distance fromthe generator without any appreciableloss from condensation orwaste of The return water may be admitted towater. the heater by means of automatic gravity-traps or feed-waterapparatus in place of pumps,-if

desired. V

- It is evident that ,many more modifications of the various featuresand parts of this invention maybe employed, which it is notideeme'd Ynecessary here to enumerate. g 7

My invention is not limited to the specific form of pressure-reducer ormeans for converting the hot water into steam shown and described; butany construction which will operate'to reduce the pressure and convertthe hot water into steam maybe employed without departing from thespirit of the invention.

The word superheated throughout this specification and the followingclaims is used to denote water heated to over2l2.

Some of the parts which are herein shown and described are shown andmore fully de- 2 scribedin Patent No. 208,633, granted to me October 1,1878, and form no part of the invention claimed herein, but .areincluded in order to more fully andclearly illustrate the said'invention.

Having now described the-nature of the said invention and explained themanner of carrying it into practical effect, I hereby declare that whatI consider to be novel and original,

and therefore claim, and desire to secure by Letters Patent of theUnited States, is

5 1. The herein-described method of furnishing steam for heat and powerpurposes to large districts of buildings in cities and towns, whichconsists in superheating water at a central station, conveying the waterto the buildings to be heated, converting the superheated wa ter intosteam, which is employed for heating purposes, and returning the waterof condensation to the heater at the station, substantially as shown anddescribed.

2. The herein-described method of furnishing heat and power for largedistricts of build ings in cities and towns, which consists in heatingwater at a central station, conveying it throughout the district to beheated and re 20 turning it to the heat-er, extracting a portion of thehot water at the points where heat or power is required, and returningthe same or a portion thereof directly to the heater after it has beenused for heat or power purposes, substantially as shown and described.

3. Theherein-described method offurnishing steam for heati ng or powerpurposes to large districts of buildings in cities and towns, whichconsists in superheating water at a central station, conveying the waterto the buildi ngs where heat or power is required, converting thesuperheated water into steam, and returning the water of condensation tothe heater,where it is reheated and again circulated, substantially asshown and described.

\VILLIAM E. PRA LL.

Witnesses:

NATHAN GUILFORD, THEO. A. VAIL.

